Battery voltage

[btgc]

As I'm lagging electrically wanted to verify this on RFF. I have a compact camera (Voigtlaender VF 101, to name) with batteries, set of 4. They read 1.55V each, loaded pack reads 3.1V - fine. Catch is I don't know real age of batteries, they don't look new shining things, but look kind of semi-matte instead. While my question may sound funny and beyond, but could be that they read correct voltage without load but fail to deliver full juice when metering?

Camera underexposes by several stops so I'm trying to justify finding the new set of 1.5V batteries (it needs 1.5V cells). When metering voltage drops to 2.3V if I do it right (multimeter connected serially). UPD: whem metering, voltage varies depending on amount of light and aperture, from 1.something (f/16, away from ) to 2.95V (f/2.8, to window).

I'm aware cells go bad and underexposure is common thing in old cameras, just wanted to crosscheck my assumptions if batteries can fail to deliver needed voltage under load even if reading right without load.

 

[Bill Clark]

Google the part number of the battery and see what comes up.

 

[Bill Clark]

More info:

http://www.cameramanuals.org/voigtlander_pdf/voigtlander_vf101.pdf

Check page 23 on battery info. Mallory and Varta # listed, try google that and see if a sub is available. You may need to compensate as 1.5 volt may be hard to come by.

 

[Dwig]

... could be that they read correct voltage without load but fail to deliver full juice when metering? ...

Yes, they could measure OK under no load conditions and fail to deliver the proper voltage when subjected to a significant load.

Since the manual specifies the 625 battery (aka PX-625) instead of the lower current PX-13, I suspect that the camera's early electronic metering requires significant current. Also, the odd arrangement of stacking pairs to produce 3.0-3.1v and then putting the two pairs in parallel to double the current available also points towards a high current load.

This need for high current may put limitations on the available substitutes. I would doubt any of the alkaline substitutes will given adequate life. Adapting a pair of CR1/3 3v lithium batteries (aka 2L76, K58L, CR1/3N, DL1/3N, 5018LC, CR11108) might be a solution. They are lithium batteries designed to replace a pair of the common S76/LR44 silver oxide batteries.

 

[Rob-F]

When metering voltage drops to 2.3V if I do it right (multimeter connected serially). UPD: whem metering, voltage varies depending on amount of light and aperture, from 1.something (f/16, away from ) to 2.95V (f/2.8, to window).

When measuring voltage you should not connect the meter in series with the load. A series connection is only used when measuring current. For a voltage measurement, the meter leads must be connected in parallel; in other words, right across the battery terminals (positive lead to positive terminal and negative lead to negative terminal). The series connection you used is no doubt mainly responsible for the strange readings you got.

 

[rick oleson]

I note you mention your problem is underexposure. Weak/undervoltage batteries would generally result in overexposure, due to the meter reading low. Underexposure could result from the battery voltage being high, although it doesn't seem very likely with an error of 0.05 volts. It depends very much on the design of the meter, though, some are more voltage-sensitive than others.

 

[Rob-F]

The most convenient and straightforward way to see if the batteries are too old, is to always keep a spare set on hand. If fresh batteries solve the problem, you have your answer. If not, the fault lies elsewhere. I am never without a spare set.

 

[Beemermark]

Just to Butkus.org site and read the instruction manual. Has directions to check the batteries.

 

[sevo]

The VF101 is supposed to use two times two PX625 mercury cells (of 1.35V each, for a total of 2.7V) - which are gone. To use it with silver oxide cells, you'd have to solder in 0.4V worth of drop diodes - but that would increase the current issues you apparently already have. I remember somebody reporting that he converted his camera to one CR123A (3V lithium) - while still over voltage that ought to be better than silver oxides (with 3.1V and your current issues).

 

[ABrosig]

Check out this link:

https://www.batteriesplus.com/search?q=px-625

Should do the trick

 

[Mr_Flibble]

I note you mention your problem is underexposure. Weak/undervoltage batteries would generally result in overexposure, due to the meter reading low. Underexposure could result from the battery voltage being high, although it doesn't seem very likely with an error of 0.05 volts. It depends very much on the design of the meter, though, some are more voltage-sensitive than others.

THIS!

Made the mistake of loading a 625A battery in a Rollei 35 camera that requires a PX-625. Camera was under exposing by 2 stops because the meter was registering high due to the higher voltage.

There are some small battery adapters out there to get that 1.35v you'll need. (or 2.7v in this case).

 

[rick oleson]

Yes, that all makes sense. If your meter was designed for mercury cells at 1.35v each and you've loaded 1.5 or 1.55v cells, you will get underexposure. One way to deal with this is to buy a set of WEIN zinc-air substitute cells, which at 1.4v are usually close enough to make the meter usable. Another is to buy a set of CRIS battery adapters which drop the voltage of a 1.55v silver cell down to 1.35v while also making it match the size of the PX625 cell. With 4 cells, either of these can be a little expensive. A cheaper way is to clean the guts out of four 625A alkaline cells (not as messy as it sounds) and use the shells as adapters to hold four 1.4v #675 zinc-air hearing aid batteries which you can get at the pharmacy for about a dollar each in multi-packs. If you don't want to do the messy part, last I knew you could buy these shells all cleaned out for you from Jon Goodman at jon_goodman@yahoo.com.

And here's all the rest of what I know about this stuff: http://rick_oleson.tripod.com/index-111.html

 

[Evanjoe610]

How about using the CRIS adapter for those old obsolete batteries and hawing the internal circuits adjusted for the higher voltage?


I understand that the CRSI adapter will auto adjust for the spike.

 

[rick oleson]

Yes, that's one of several options mentioned above. But, at $37 each, it's quite a bit of money for a camera that needs 4 of them....